The present invention relates to a polyurethane composition, and more particularly to a polyurethane composition having an improved lipophilic property.
Polyurethane resins are prepared by reacting the hydroxyl group of polyols and isocyanate group of polyisocyanate compounds. For instance, polypropylene glycol and polytetramethylene-ether glycol have been used as the polyols, and toluene diisocyanate and 4,4'-diphenylmethane diisocyanate have been used as the polyisocyanates. Catalysts, pigments, foaming agents, silicone surface active agents, and the like have also been used, as occasion demands.
Conventional polyurethane resins have the disadvantage that they are poor in lipophilic property or water resistance. The polyols used are not compatible with aliphatic hydrocarbon compounds, and the obtained polyurethane resins, in other words, products crosslinked with polyisocyanates, are also not compatible with the aliphatic hydrocarbon compounds. Accordingly, it is difficult to conduct the reaction for formation of polyurethane in petroleum oily substances, and the application and development of this technique have been greatly restricted.
Also, in order to improve the lipophilic property or water resistance of polyurethane resins, it is proposed to use polyalkylene polyols, e.g. a hydroxy-terminated polyolefin such as polyethylene or polybutadiene wherein hydroxy substituent groups are introduced into the polymer ends, and a hydrogenation product of a hydroxy-terminated polyolefin having unsaturated bonds in the side chains. However, this technique has the disadvantages that the structure of the polyols is limited in the molecular weight and the number of functional groups, and that the use of additives such as dyes, pigments and catalysts is also limited, and that since the viscosity of these polyols is very high, the workability and the processability are bad and the usages have been remarkably limited, and further that the polyols are expensive because of complicated production steps.
In order to decrease the high viscosity of polyalkylene polyols, it is also proposed to use the polyols in combination with a castor oil-propylene oxide polyol as a viscosity reducer. However, the castor oil-propylene oxide polyol is unstable because of containing ester bond, and may cause a problem when used in the winter because of high melting point. Also, since it is impossible to control the number of functional groups, the application of the obtained polyurethane is limited from the point of physical properties.
The polyalkylene polyols have a further disadvantage that they are poor in compatibility with polyether polyols which have been usually used for the production of polyurethane resins, and even if mixed together, the mixture separates into layers with the lapse of time, thus the desired polyurethane resins are obtained with difficulty.
It is an object of the present invention to eliminate the above-mentioned defects of conventional polyurethane resins.
A further object of the present invention is to provide a polyurethane composition capable of giving a polyurethane resin having an improved lipophilic property.
Another object of the present invention is to provide a polyurethane resin containing aliphatic hydrocarbon compounds.
Still another object of the present invention is to provide a polyurethane composition having excellent processability and workability and capable of giving a polyurethane having an improved water resistance.
These and other objects of the present invention will become apparent from the description hereinafter.